Grandson turned 18 and all child support payments stopped. Do you stop collection on payments in arrears?

Q) We had guardianship of our grandson for 8 years. The Courts awarded child support from both mother and father, both are in great arrears. When our grandson turned 18 and graduated school all child support payments stopped and we stopped getting statements. However our account was charged even though no monies were collected. Do you stop collection on payments in arrears once the child turns 18?

A) Rules for Back Child Support: Regardless of state differences on the age of majority, once the child is officially considered an adult, the custodial parent will not be owed any new child support payments. However, any outstanding payments are still collectible provided the parent files a court order. Source: https://family-law.freeadvice.com/family-law/child_support/back_child_support.htm